Background: Lobular carcinoma in situ (LCIS) is known to be a risk factor for the development of invasive breast cancer. Debate continues as to whether LCIS is also a precursor lesion. We hypothesized that, if LCIS were a precursor, its presence in the lumpectomy specimen, particularly at the margin, could increase local recurrence (LR) after breast-conserving therapy (BCT).
Methods: 2894 patients treated with BCT for ductal carcinoma in situ (DCIS), stage I or II breast cancer between 1/80 and 5/07 were identified. Patients with DCIS or invasive cancer at the margins or those receiving neoadjuvant therapy were excluded. Group A had 290 patients with LCIS in the lumpectomy; 84 had LCIS at the final margin. Group B included 2604 patients with no evidence of LCIS.
Results: Median patient age in group A and B was 57 and 58 years, respectively (P = 0.05); 12% and 13%, respectively, of patients in group A and B had margins <2 mm (P = NS). The histologic distribution of tumor types in group A was lobular in 47.2%, ductal in 34.5%, DCIS in 11.4%, and other invasive histologies in 6.9%, compared with 4.1%, 76.3%,13.6%, and 6.0% for group B, respectively (P < 0.0001). There was no significant difference between the groups in tumor-node-metastasis (TNM) stage. The crude rate of LR was 4.5% in group A and 3.8% in group B (P = NS). Five- and 10-year actuarial LR rates for LCIS at the margin were 6% and 6%, 1% and 15% for LCIS present but not at the margin, and 2% and 6% for no LCIS (P = NS), for group A and B, respectively. In multivariate analysis, menopausal status and adjuvant therapy use were significant predictors of LR. LCIS, either in the specimen or at the margin, was not significantly associated with LR.
Conclusion: Presence of LCIS, even at the margin, in BCT specimens does not have an impact on LR. Re-excision is not indicated if LCIS is present or close to margin surfaces. These findings do not support consideration of LCIS as a precursor to the development of invasive lesions.